From 53a20308de310b0493ae542a827151dec3a9179b Mon Sep 17 00:00:00 2001
From: Daniel Goldberg <danielg@guardicore.com>
Date: Sun, 10 Sep 2017 10:36:00 +0300
Subject: [PATCH] Rewrite get_host_subnets, drastically simplify Linux
 implementation. Cleanup code in get_ips_from_interfaces

Modern python

bug fix
---
 chaos_monkey/network/info.py | 102 ++++++++++++++---------------------
 1 file changed, 41 insertions(+), 61 deletions(-)

diff --git a/chaos_monkey/network/info.py b/chaos_monkey/network/info.py
index 59b40a089..6c014a609 100644
--- a/chaos_monkey/network/info.py
+++ b/chaos_monkey/network/info.py
@@ -1,34 +1,34 @@
 import os
 import sys
-import array
 import socket
 import struct
 import psutil
 import ipaddress
+import itertools
+import netifaces
 from subprocess import check_output
 from random import randint
 
 if sys.platform == "win32":
-    import netifaces
-
 
     def local_ips():
         local_hostname = socket.gethostname()
         return socket.gethostbyname_ex(local_hostname)[2]
 
 
-    def get_host_subnets(only_ips=False):
-        network_adapters = []
-        valid_ips = local_ips()
-        if only_ips:
-            return valid_ips
-        interfaces = [netifaces.ifaddresses(x) for x in netifaces.interfaces()]
-        for inte in interfaces:
-            if netifaces.AF_INET in inte:
-                for add in inte[netifaces.AF_INET]:
-                    if "netmask" in add and add["addr"] in valid_ips:
-                        network_adapters.append((add["addr"], add["netmask"]))
-        return network_adapters
+    def get_host_subnets():
+        ipv4_nets = [netifaces.ifaddresses(interface)[netifaces.AF_INET]
+                     for interface in netifaces.interfaces()
+                     if netifaces.AF_INET in netifaces.ifaddresses(interface)
+                     ]
+        # flatten
+        ipv4_nets = itertools.chain.from_iterable(ipv4_nets)
+        # remove loopback
+        ipv4_nets = [network for network in ipv4_nets if network['addr'] != '127.0.0.1']
+        # remove auto conf
+        ipv4_nets = [network for network in ipv4_nets if not network['addr'].startswith('169.254')]
+        return ipv4_nets
+
 
     def get_routes():
         raise NotImplementedError()
@@ -36,46 +36,26 @@ if sys.platform == "win32":
 else:
     from fcntl import ioctl
 
-    def get_host_subnets(only_ips=False):
-        """Get the list of Linux network adapters."""
-        max_bytes = 8096
-        is_64bits = sys.maxsize > 2 ** 32
-        if is_64bits:
-            offset1 = 16
-            offset2 = 40
-        else:
-            offset1 = 32
-            offset2 = 32
-        sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
-        names = array.array('B', '\0' * max_bytes)
-        outbytes = struct.unpack('iL', ioctl(
-            sock.fileno(),
-            0x8912,
-            struct.pack('iL', max_bytes, names.buffer_info()[0])))[0]
-        adapter_names = [names.tostring()[n_cnt:n_cnt + offset1].split('\0', 1)[0]
-                         for n_cnt in xrange(0, outbytes, offset2)]
-        network_adapters = []
-        for adapter_name in adapter_names:
-            ip_address = socket.inet_ntoa(ioctl(
-                sock.fileno(),
-                0x8915,
-                struct.pack('256s', adapter_name))[20:24])
-            if ip_address.startswith('127'):
-                continue
-            subnet_mask = socket.inet_ntoa(ioctl(
-                sock.fileno(),
-                0x891b,
-                struct.pack('256s', adapter_name))[20:24])
 
-            if only_ips:
-                network_adapters.append(ip_address)
-            else:
-                network_adapters.append((ip_address, subnet_mask))
+    def get_host_subnets():
+        ipv4_nets = [netifaces.ifaddresses(interface)[netifaces.AF_INET]
+                     for interface in netifaces.interfaces()
+                     if netifaces.AF_INET in netifaces.ifaddresses(interface)
+                     ]
+        # flatten
+        ipv4_nets = list(itertools.chain.from_iterable(ipv4_nets))
+        # remove loopback
+        ipv4_nets = [network for network in ipv4_nets if network['addr'] != '127.0.0.1']
+        # remove auto conf
+        ipv4_nets = [network for network in ipv4_nets if not network['addr'].startswith('169.254')]
+        return ipv4_nets
 
-        return network_adapters
 
     def local_ips():
-        return get_host_subnets(only_ips=True)
+        ipv4_nets = get_host_subnets()
+        valid_ips = [network['addr'] for network in ipv4_nets]
+        return valid_ips
+
 
     def get_routes():  # based on scapy implementation for route parsing
         LOOPBACK_NAME = "lo"
@@ -151,17 +131,17 @@ def check_internet_access(services):
 def get_ips_from_interfaces():
     res = []
     ifs = get_host_subnets()
-    for interface in ifs:
-        ipint = ipaddress.ip_interface(u"%s/%s" % interface)
+    for net_interface in ifs:
+        host_addr = ipaddress.ip_address(net_interface['addr'])
+        ip_interface = ipaddress.ip_interface(u"%s/%s" % (net_interface['addr'], net_interface['netmask']))
         # limit subnet scans to class C only
-        if ipint.network.num_addresses > 255:
-            ipint = ipaddress.ip_interface(u"%s/24" % interface[0])
-        for addr in ipint.network.hosts():
-            if str(addr) == interface[0]:
-                continue
-            res.append(str(addr))
+        if ip_interface.network.num_addresses > 255:
+            ip_interface = ipaddress.ip_interface(u"%s/24" % net_interface['addr'])
+        addrs = [str(addr) for addr in ip_interface.network.hosts() if addr != host_addr]
+        res.extend(addrs)
     return res
 
+
 if sys.platform == "win32":
     def get_ip_for_connection(target_ip):
         return None
@@ -171,7 +151,7 @@ else:
             query_str = 'ip route get %s' % target_ip
             resp = check_output(query_str.split())
             substr = resp.split()
-            src = substr[substr.index('src')+1]
+            src = substr[substr.index('src') + 1]
             return src
         except Exception:
-            return None
\ No newline at end of file
+            return None